Process for the production of detergent or cleaning tablets

ABSTRACT

A process for producing detergent tablets containing more than 10% by weight of anionic surfactant wherein the detergent tablets contain detergent components which are at least partly in hydrated form and the anionic surfactant is present in the form of one or more compounds containing up to 95% by weight of surfactants, by exposing a mixture of the detergent components and the anionic surfactant to microwaves in the frequency range from 3 to 300,000 MHz.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for the production ofsurfactant-containing detergent or cleaning tablets using microwaves.

The disadvantage of conventional detergent or cleaning tablets,particularly detergent tablets, which are normally produced bycompression molding was that these tablets did not dissolve sufficientlyquickly on account of their compactness and the active substances werereleased too slowly in the wash cycle. In addition, detergent tablets inparticular had an inadequate disintegration rate.

2. Discussion of Related Art

Earlier hitherto unpublished International patent applicationPCT/EP94/01330, to the disclosure of which reference is specificallymade, describes in detail the production of washing- and cleaning-activetablets with an extremely high dissolving or disintegration rate usingmicrowaves. A crucial requirement for the production of tablets frompowder-form or granular raw materials using microwaves is that thesestarting materials should be at least partly present in hydrated form,"hydrated" meaning "hydrated under certain conditions in regard to thetemperature, pressure or relative humidity of the atmosphere to whichthe raw material is exposed or with which the raw material is inequilibrium". By "microwaves" in the context of the invention is meantthe entire frequency range from 3 to 300,000 MHz which covers not onlythe actual microwave range above 300 MHz, but also the radio wave rangefrom 3 to 300 MHz. So-called macrosolids, including for example blocksin addition to tablets, which may normally contain up to 40% by weightof surfactants can be produced by this technique. If one of the rawmaterials used in substantial quantities is a crystalline layersilicate, more particularly of the SKS-6® type (crystalline sodiumdisilicate, a product of Hoechst AG, Germany), the surfactant contentmay even be as high as 60% by weight. Other possible ingredients are, onthe one hand, the microwave-active hydrated inorganic or organic salts,such as alkali metal phosphate, alkali metal carbonate, alkali metalbicarbonate, alkali metal sulfate and citrate, and also zeolite and evenperoxy bleaching agents, such as perborate or percarbonate. These arepreferably used in encapsulated form.

Difficulties are still involved in the production of microwave tabletscontaining anionic surfactants in substantial quantities, for example inquantities above 10% by weight, and inorganic salts in quantities below60% by weight. Although tablets such as these can be produced on anindustrial scale in accordance with the teaching of PCT/EP94/01330,sulfate- and sulfonate-containing anionic surfactants in particular tendto turn brown in color in concentrations as high as these so that,although washing performance is not affected, the discoloration is notaccepted by the consumer. In addition, the dissolving behavior of thetablets deteriorates with increasing surfactant content.

It has now been found that the dissolving behavior ofsurfactant-containing microwave tablets can be increased providing asignificant proportion of the surfactants is not incorporated in thetablets as an individual raw material.

DESCRIPTION OF THE INVENTION

Accordingly, the present invention relates to a process for theproduction of detergent or cleaning tablets containing anionicsurfactants, characterized in that the tablets are produced usingmicrowaves and in that the anionic surfactants are introduced into theprocess in the form of one or more compounds.

The use of such surfactant compounds, including highly concentratedsurfactant compounds with contents of up to about 95% by weight ofsurfactants, leads to local differences in the concentration ofsurfactants in the tablet which has an advantageous effect not onlyduring processing, but also during the subsequent disintegration of thetablet in the wash liquid.

The anionic surfactants used are, for example, those of the sulfonateand sulfate types. Preferred surfactants of the sulfonate type are C₉₋₁₃alkyl benzene sulfonates, olefin sulfonates, i.e. mixtures of alkene andhydroxyalkane sulfonates and disulfonates which are obtained, forexample, from C₁₂₋₁₈ monoolefins with a terminal or internal double bondby sulfonation with gaseous sulfur trioxide and subsequent alkaline oracidic hydrolysis of the sulfonation products. Other suitable anionicsurfactants are alkane sulfonates which are obtained from C₁₂₋₁₈alkanes, for example by sulfochlorination or sulfoxidation andsubsequent hydrolysis or neutralization. The esters of α-sulfofattyacids (ester sulfonates), for example the α-sulfonated methyl esters ofhydrogenated coconut oil, palm kernel oil or tallow fatty acids, arealso suitable anionic surfactants.

Other suitable anionic surfactants are sulfonated fatty acid glycerolesters. Fatty acid glycerol esters in the context of the invention areunderstood to be the mono-, di- and triesters and mixtures thereof whichare obtained where production is carried out by esterification of amonoglycerol with 1 to 3 moles of fatty acid or in thetransesterification of triglycerides with 0.3 to 2 moles of glycerol.Preferred sulfonated fatty acid glycerol esters are the sulfonationproducts of saturated fatty acids containing 6 to 22 carbon atoms, forexample caproic acid, caprylic acid, capric acid, myristic acid, lauricacid, palmitic acid, stearic acid or behenic acid. If fats and oils,i.e. natural mixtures of different fatty acid glycerol esters, are usedas starting materials, they have to be substantially saturated withhydrogen in known manner before sulfonation, i.e. hydrogenated to iodinevalues below 5 and advantageously below 2. Typical examples of suitablestarting materials are palm oil, palm kernel oil, palm stearin, oliveoil, rapeseed oil, coriander oil, sunflower oil, cottonseed oil, peanutoil, linseed oil, lard oil or lard. However, it has proved to be ofparticular advantage to use coconut oil, palm kernel oil or beef tallowas starting material by virtue of their high natural content ofsaturated fatty acids. The sulfonation of the saturated fatty acidscontaining 6 to 22 carbon atoms or the mixtures of fatty acid glycerolesters with iodine values below 5, which contain C₆₋₂₂ fatty acids, ispreferably carried out by reaction with gaseous sulfur trioxide andsubsequent neutralization with aqueous bases, as described inInternational patent application WO-A-91/09009. The sulfonation productsare a complex mixture which contains mono-, di- and triglyceridesulfonates with a sulfonic acid group in the α-position and/or aninternal sulfonic acid group. Sulfonated fatty acid salts, glyceridesulfates, glycerol sulfates, glycerol and soaps are formed as secondaryproducts. If saturated fatty acids or hydrogenated fatty acid glycerolester mixtures are used as starting material for the sulfonation, thepercentage content of α-sulfonated fatty acid disalts may easily be ashigh as about 60% by weight, depending on how the process is carriedout.

Suitable surfactants of the sulfate type are the sulfuric acidmonoesters of primary alcohols of natural and synthetic origin.Preferred alk(en)yl sulfates are the alkali metal salts and especiallythe sodium salts of sulfuric acid semiesters of C₁₂₋₁₈ fatty alcohols,for example coconut fatty alcohol, tallow fatty alcohol, lauryl,myristyl, cetyl or stearyl alcohol, or the C₁₀₋₂₀ oxoalcohols and thesemiesters of secondary alcohols with the same chain length. Otherpreferred alk(en)yl sulfates are those with the chain length mentionedwhich contain a synthetic linear alkyl group based on petrochemicalswhich are comparable in their degradation behavior to the correspondingcompounds based on oleochemical raw materials. C₁₆₋₁₈ alk(en)yl sulfatesare particularly preferred from the point of view of washingperformance. It can also be of particular advantage, especially formachine detergents, to use C₁₆₋₁₈ alk(en)yl sulfates in combination withlow melting anionic surfactants and, more particularly, with anionicsurfactants which have a relatively low Krafft point and which show onlya slight tendency to crystallize at relatively low washing temperatures,for example from room temperature to 40° C. In one preferred embodimentof the invention, therefore, the detergents contain mixtures ofshort-chain and long-chain fatty alkyl sulfates, preferably C₁₂₋₁₈ fattyalkyl sulfates or mixtures of C₁₂₋₁₄ fatty alkyl sulfates or C₁₂₋₁₈fatty alkyl sulfates with C₁₆₋₁₈ fatty alkyl sulfates and, moreparticularly, C₁₂₋₁₆ fatty alkyl sulfates with C₁₆₋₁₈ fatty alkylsulfates. In another preferred embodiment of the invention, however,unsaturated alkenyl sulfates with an alkenyl chain length of,preferably, C₁₆ to C₂₂ are used in addition to saturated alkyl sulfates.Particular preference is attributed in this regard to mixtures ofsaturated sulfonated fatty alcohols consisting predominantly of C₁₆ andunsaturated sulfonated fatty alcohols consisting predominantly of C₁₈,for example those derived from solid or liquid fatty alcohol mixtures ofthe HD-Ocenol® type (a product of Henkel KGaA). Ratios by weight ofalkyl sulfates to alkenyl sulfates of 10:1 to 1:2 are preferred, ratiosby weight of about 5:1 to 1:1 being particularly preferred.

The sulfuric acid monoesters of linear or branched C₇₋₂₁ alcoholsethoxylated with 1 to 6 moles of ethylene oxide, such as2-methyl-branched C₉₋₁₁ alcohols containing on average 3.5 moles ofethylene oxide (EO) or C₁₂₋₁₈ fatty alcohols containing 1 to 4 EO, arealso suitable. In view of their high foaming power, they are used indetergents in only relatively small quantities, for example inquantities of 1 to 5% by weight.

Other suitable anionic surfactants are the salts of alkyl sulfosuccinicacid which are also known as sulfosuccinates or as sulfosuccinic acidesters and which represent monoesters and/or diesters of sulfosuccinicacid with alcohols, preferably fatty alcohols and, more preferably,ethoxylated fatty alcohols. Preferred sulfosuccinates contain C₈₋₁₈fatty alcohol residues or mixtures thereof. Particularly preferredsulfosuccinates contain a fatty alcohol residue derived from ethoxylatedfatty alcohols which, for their part, are nonionic surfactants (for adescription, see below). Among these sulfosuccinates, those of which thefatty alcohol residues are derived from narrow-range ethoxylated fattyalcohols are particularly preferred. Alk(en)yl succinic acid preferablycontaining 8 to 18 carbon atoms in the alk(en)yl chain or salts thereofmay also be used.

Other suitable anionic surfactants are, in particular, soaps. Suitablesoaps are saturated fatty acid soaps, such as the salts of lauric acid,myristic acid, palmitic acid, stearic acid, hydrogenated erucic acid andbehenic acid, and soap mixtures derived in particular from natural fattyacids, for example coconut fatty acid, palm kernel fatty acid or tallowfatty acid. Soap mixtures of which 50 to 100% by weight consist ofsaturated C₁₂₋₂₄ fatty acid soaps and 0 to 50% by weight of oleic acidsoap are particularly preferred.

The anionic surfactants and soaps may be present in the form of theirsodium, potassium or ammonium salts and as soluble salts of organicbases, such as mono-, di- or triethanolamine. The anionic surfactantsare preferably present in the form of their sodium or potassium salts,more particularly in the form of their sodium salts.

In addition to anionic surfactants, nonionic, cationic, zwitterionic oramphoteric surfactants may be used in the tablets and, optionally, evenin the anionic-surfactant-containing compounds. Nonionic surfactants areparticularly preferred.

The nonionic surfactants used are preferably alkoxylated, advantageouslyethoxylated, more especially primary alcohols containing preferably 8 to18 carbon atoms and, on average, 1 to 12 moles of ethylene oxide (EO)per mole of alcohol, in which the alcohol radical may be linear orpreferably 2-methyl-branched or may contain linear and methyl-branchedradicals in the form of the mixtures typically present in oxoalcoholradicals. However, alcohol ethoxylates containing linear C₁₂₋₁₈ alcoholradicals of native origin, for example coconut, palm kernel, tallow oroleyl alcohol, and on average 2 to 8 EO per mole of alcohol areparticularly preferred. Preferred ethoxylated alcohols include, forexample, C₁₂₋₁₄ alcohols containing 3 EO or 4 EO, C₉₋₁₁ alcoholcontaining 7 EO, C₁₃₋₁₅ alcohols containing 3 EO, 5 EO, 7 EO or 8 EO,C₁₂₋₁₈ alcohols containing 3 EO, 5 EO or 7 EO and mixtures thereof, suchas mixtures of C₁₂₋₁₄ alcohol containing 3 EO and C₁₂₋₁₈ alcoholcontaining 5 EO. The degrees of ethoxylation mentioned are statisticalmean values which, for a special product, may be a whole number or abroken number. Preferred alcohol ethoxylates have a narrow homologdistribution (narrow range ethoxylates, NRE). In addition to thesenonionic surfactants, fatty alcohols containing more than 12 EO may alsobe used. Examples of such fatty alcohols are tallow fatty alcoholcontaining 14 EO, 25 EO, 30 EO or 40 EO.

Other suitable nonionic surfactants are alkyl glycosides correspondingto the general formula RO(G)_(x), in which R is a primary, linear ormethyl-branched, more especially 2-methyl-branched, aliphatic radicalcontaining 8 to 22 carbon atoms and preferably 12 to 18 carbon atoms andG stands for a glycose unit containing 5 or 6 carbon atoms, preferablyglucose. The degree of oligomerization x, which indicates thedistribution of monoglycosides and oligoglycosides, is a number of 1 to10, preferred values for x being 1.2 to 1.4.

Another class of preferred nonionic surfactants, which are used eitheras sole nonionic surfactant or in combination with other nonionicsurfactants, are alkoxylated, preferably ethoxylated or ethoxylated andpropoxylated, fatty acid alkyl esters, preferably containing 1 to 4carbon atoms in the alkyl chain, more particularly the fatty acid methylesters which are described, for example, in Japanese patent applicationJP 58/217598 or which are preferably produced by the process describedin International patent application WO-A-90/13533.

Nonionic surfactants of the amine oxide type, for exampleN-cocoalkyl-N,N-dimethyl amine oxide and N-tallowalkyl-N,N-dihydroxyethyl amine oxide, and the fatty acid alkanolamidetype are also suitable. The quantity in which these nonionic surfactantsare used is preferably no more than the quantity in which theethoxylated fatty alcohols are used and, more preferably, is no morethan half that quantity.

Other suitable surfactants are polyhydroxyfatty acid amidescorresponding to formula (I): ##STR1## in which R² CO is an aliphaticacyl group containing 6 to 22 carbon atoms, R³ is hydrogen, an alkyl orhydroxyalkyl group containing 1 to 4 carbon atoms and Z! is a linear orbranched polyhydroxyalkyl group containing 3 to 10 carbon atoms and 3 to10 hydroxyl groups. The polyhydroxyfatty acid amides are knownsubstances which may normally be obtained by reductive amination of areducing sugar with ammonia, an alkylamine or an alkanolamine andsubsequent acylation with a fatty acid, a fatty acid alkyl ester or afatty acid chloride.

One preferred embodiment of the invention is characterized by the use ofanionic-surfactant-containing compounds which contain different anionicsurfactants--for example alkyl sulfates and alkyl benzene sulfonatesand/or soap or alkyl sulfates and sulfonated fatty acid glycerolesters--and/or anionic surfactants in combination with nonionicsurfactants--for example alkyl sulfates and ethoxylated fatty alcoholsor alkyl sulfates, alkyl benzene sulfonates, ethoxylated fatty alcoholsand/or alkyl glycosides or alkyl sulfates, soap, ethoxylated fattyalcohols and glucamides. The compounds in question are preferablycompounds containing anionic and nonionic surfactants in a ratio byweight of 10:1 to 1:1.

Preferred compounds have a surfactant content of at least 10% by weight.Another preferred embodiment of the invention is characterized by theuse of compounds containing at least 40% by weight and preferably 60 to95% by weight, based on the compound, of anionic surfactants.

In another preferred embodiment of the invention, compounds of at leasttwo different types are used in the process. For example, anionicsurfactants and nonionic surfactants may be separated from one anotherin space to a very considerable extent, i.e. may be accommodated indifferent compounds. Compounds which contain nonionic surfactants, butno anionic surfactants, may contain for example 40 to 70% by weight ofthe nonionic surfactants mentioned and also known silicates and organicbuilders, such as polymeric polycarboxylates and/or phosphonates.

In particularly advantageous embodiments of the invention, at least 35%by weight, preferably at least 50% by weight and more preferably atleast 70% by weight of the overall formulation of the detergent orcleaning tablet consists of one or more different compounds. In oneparticularly advantageous process, at least 70% by weight and up to 100%by weight of the overall formulation may be initially introduced as anoptionally aftertreated compound.

In this way, conventional and commercially available detergents orcleaning products in which at least one compound containing anionicsurfactants is present may be converted into tablets by the processaccording to the invention. Examples of such detergents or cleaningproducts are spray-dried detergents with apparent densities of around300 to 600 g/l which preferably contain 5 to 40% by weight of anionicsurfactants in the spray-dried components. These spray-dried granulesmay even be subsequently sprayed or "powdered" with other ingredients ofdetergents or cleaners under granulated conditions so that theirapparent density is increased. Preferred liquid ingredients are nonionicsurfactants while preferred powdering agents are, for example,fine-particle zeolites, silicas, sulfates and/or calcium stearates. Inother preferred detergents or cleaners, spray-dried granules containinganionic surfactants are present alongside spray-dried or granulatedcompounds which consist of carrier materials, such as zeolite,crystalline layer silicates, polymeric polycarboxylates, carbonates and,optionally, even silicates and which are impregnated with liquid topaste-like or wax-like ingredients, such as nonionic surfactants and/orfoam inhibitors or conventional fabric softeners.

In another embodiment, the present invention relates not only tospray-dried detergents or cleaning formulations, but also to granulatedor extruded detergents or cleaning formulations which are produced, forexample, by the processes according to European patent applicationsEP-A-0 339 996, EP-A-0 420 317 or International patent applicationsWO-A-93/23523 or WO-A-91/02047.

It is of course also possible and even preferred in the context of thepresent invention not only to convert already present formulations ofthe type in question into tablet form in the described manner, but alsoto mix separately prepared compounds optionally with relatively smallquantities of individual components and to convert the resulting mixtureinto tablet form using microwaves. Thus, spray-dried granules containinganionic surfactants can be tabletted together with zeolite-containinggranules sprayed with nonionic surfactants and/or together withindividual extrudates, for example extrudates containing enzymes orbleach activators or even peroxy bleaching agents, by the microwavetechnique. It is also possible to use various forms of extrudates, forexample those produced by the process according to earlier German patentapplication P 44 06 210.9, for microwave tabletting. The compounds usedmay also be of the type produced by drying with super-heated steam ormicrowaves.

In one preferred embodiment of the invention, however, compounds withhigh anionic surfactant contents of above 40% by weight and preferablyup to 90% by weight or higher, which are produced in particular bygranulation and simultaneous drying, advantageously by the fluidized bedprocess described in International patent application WO 93/04162, areused at least as one of several compounds.

If the compound-containing mixtures mentioned above are exposed tomicrowaves in accordance with International patent applicationPCT/EP94/01330, the compounds are fused together at the points ofcontact as a result of local melting/sintering. The voids presentbetween the individual compounds before the exposure to microwavesensure that the tablet formed is highly porous and thus contributetowards improving the dissolving properties of the tablet.

To ensure that local sintering of the compounds is possible in the firstplace, at least some of them must have sintering properties at theirsurfaces. To this end, the compounds themselves or their surfaces mustcontain sufficient water so that the compounds melt at their points ofcontact when the water is heated. According to the teaching ofInternational patent application PCT/EP94/01330, at least part of themixture to be exposed to microwaves must be present in hydrated form,"hydrated" meaning "hydrated under certain conditions in regard to thetemperature, pressure or relative humidity of the atmosphere to whichthe raw material is exposed or with which the raw material is inequilibrium".

Accordingly, one embodiment of the invention is characterized by the useof compounds partly containing starting materials present in hydratedform. If these water-containing components are not present in thecompounds in a quantity sufficient for sintering, if at all, thecompounds may be completely or partly encapsulated with these substancesin sufficient quantities before microwave tabletting. Particularlypreferred encapsulating substances are amorphous silicates, such asmetasilicates or waterglasses, alkali metal carbonates and alkali metalsulfates, zeolites, such as zeolite A, X, Y or P, more particularlyzeolite A and P or mixtures thereof, but also organic components, suchas water-containing citrates, for example sodium citrate dihydrate, orwater-containing acetates, for example sodium acetate trihydrate. Theseencapsulating substances are advantageously introduced into the processin quantities of 1 to 30% by weight, based on the formulation as awhole.

The formulation as a whole consisting of the individual compounds andoptionally other individual non-surface-active raw materials, which neednot be present in compound form, is introduced into a mold and exposedto microwaves in accordance with PCT/EP94/01330. The microwave treatmentleads to elevated temperatures and to local sintering of the compoundsat the points of contact, the voids remaining intact in the molding,i.e. complete fusion of the compounds to one another is avoided.Accordingly, the compounds themselves do not have to withstandrelatively high temperatures. This method of sintering results in asurprisingly high breaking strength of the tablet so that it can behandled and, in particular, transported without any problems.

If, nevertheless, this process should produce tablets lacking sufficientstability in strength, even in dependence upon the formulation, thisproblem may have arisen from the fact that the filling density of themold was not high enough, i.e. the compounds did not have a sufficientnumber of mutual contact points through normal filling of the mold. Inthis case, assistance can be provided by a process in which the filledmold is subjected to light precompression before the microwavetreatment. Any (pre)compression process known to the expert is suitablefor this purpose. The precompressions are preferably carried out underpressures of 0.1 to 5 bar and, more particularly, 0.1 to 2 bar,corresponding respectively to 1-50 N/cm² and 1-20 N/m². Sufficientlylarge contact points between the individual compounds in the tablet areobtained in this way.

In another preferred embodiment of the invention, disintegrating agentsare incorporated in the tablets, causing them to break up after cominginto contact with water. Typical disintegrating agents which arepreferably used in this process are, for example, citric acid orcitrates, bicarbonates and carbonates, bisulfate and also percarbonate.By virtue of the relatively low temperatures occurring in this process,peroxy bleaching agents, such as perborate and even percarbonate, may beincorporated in the tablets. Other preferred disintegrating agents aremicrocrystalline cellulose, sugars, more particularly sorbitol, andlayer silicates, more especially fine-particle and swellable layersilicates of the bentonite or smectite type. Disintegrating agents ofthe described type may be used in quantities of 0.5 to 30% by weight andpreferably in quantities of 1 to 25% by weight, based on the formulationas a whole. The disintegrating agents may be used either as anindividual raw material or again in the form of a compound.

If the residual moisture content of the overall mixture to be usedshould exceed around 5 to 10% by weight, it is advisable to protect thedisintegrating agents against this moisture. Accordingly, one preferredembodiment of the invention is characterized by the use ofdisintegrating agents which are encapsulated before use with knownhydrophobic components. Paraffin oil or silicone oil--which is alsopreferably used--are mentioned purely by way of example as encapsulatingsubstances at this juncture.

As described in earlier application PCT/EP94/01330, the tablets may beaftertreated with other substances, preferably ingredients of detergentsor cleaning products, more particularly ingredients which are sensitiveto microwaves. Enzymes and perfumes are particularly mentioned in thisregard. However, it may be regarded as particularly advantageous that,by virtue of the better possible temperature control or rather therelatively low exposure of the mixture as a whole to high temperatures,enzymes can also be included in the microwave treatment in the processaccording to the invention and no longer have to be subsequently added.

The tablets may contain any typical ingredients of detergents orcleaning products in their overall formulation. Besides the surfactantsalready described in detail, these ingredients include in particularinorganic and organic builders, components which prevent resoiling offabrics (soil repellents) and redeposition inhibitors, alkaline salts,bleaching agents and bleach activators, foam inhibitors, fabricsofteners, neutral salts and dyes and fragrances.

Besides the conventional phosphates, suitable inorganic builders are, inparticular, alumosilicates of the zeolite type. The finely crystalline,synthetic zeolite containing bound water preferably used isdetergent-quality zeolite NaA. However, zeolite X and zeolite P andmixtures of A, X and/or P are also suitable.

Suitable substitutes or partial substitutes for phosphates and zeolitesare crystalline layer-form sodium silicates corresponding to the generalformula NaMSi_(x) O_(2x+1).yH₂ O, where M is sodium or hydrogen, x is anumber of 1.9 to 4 and y is a number of 0 to 20, preferred values for xbeing 2, 3 or 4. Corresponding crystalline layer silicates aredescribed, for example, in European patent application EP-A-0 164 514.Preferred crystalline layer silicates are those in which M stands forsodium and x assumes the value 2 or 3. Both β- and δ-sodium disilicatesNa₂ Si₂ O₅.yH₂ O are particularly preferred.

Useful organic builders are, for example, the polycarboxylic acidspreferably used in the form of their sodium salts, such as citric acid,adipic acid, succinic acid, glutaric acid, tartaric acid, sugar acids,aminocarboxylic acids, nitrilotriacetic acid (NTA), providing their useis ecologically safe, and mixtures thereof. Preferred salts are thesalts of polycarboxylic acids, such as citric acid, adipic acid,succinic acid, glutaric acid, tartaric acid, sugar acids and mixturesthereof.

Suitable polymeric polycarboxylates are, for example, the sodium saltsof polyacrylic acid or polymethacrylic acid, for example those with arelative molecular weight of 800 to 150,000 (based on acid). Suitablecopolymeric polycarboxylates are, in particular, those of acrylic acidwith methacrylic acid and those of acrylic acid or methacrylic acid withmaleic acid. Copolymers of acrylic acid with maleic acid which contain50 to 90% by weight of acrylic acid and 50 to 10% by weight of maleicacid have proved to be particularly suitable. Their relative molecularweight, based on free acids, is generally in the range from 5,000 to200,000, preferably in the range from 10,000 to 120,000 and morepreferably in the range from 50,000 to 100,000. Biodegradableterpolymers, for example those containing salts of acrylic acid andmaleic acid and also vinyl alcohol or vinyl alcohol derivatives asmonomers (P 43 00 772.5) or salts of acrylic acid and 2-alkyl allylsulfonic acid and sugar derivatives as monomers (DE 42 21 381), are alsoparticularly referred.

Other suitable builder systems are oxidation products ofcarboxyfunctional polyglucosans and/or water-soluble salts thereof whichare described, for example, in International patent applicationWO-A-93/08251 or of which the production is described, for example, inInternational patent application WO-A-93/16110.

The known polyaspartic acids and salts and derivatives thereof are alsomentioned as preferred builders.

Other suitable builders are polyacetals which may be obtained byreaction of dialdehydes with polyol carboxylic acids containing 5 to 7carbon atoms and at least three hydroxyl groups, for example asdescribed in European patent application EP-A-0 280 223. Preferredpolyacetals are obtained from dialdehydes, such as glyoxal,glutaraldehyde, terephthalaldehyde and mixtures thereof and from polyolcarboxylic acids, such as gluconic acid and/or glucoheptonic acid.

The inorganic and/or organic builders are preferably used in the tabletsin quantities of around 10 to 60% by weight and, more particularly, 15to 50% by weight.

In addition, the detergents/cleaners may also contain components with apositive effect on the removability of oil and fats from textiles bywashing. This effect becomes particularly clear when a textile which hasalready been repeatedly washed with a detergent according to theinvention containing this oil- and fat-dissolving component is soiled.Preferred oil- and fat-dissolving components include, for example,nonionic cellulose ethers, such as methyl cellulose and, in particular,methyl hydroxypropyl cellulose containing 15 to 30% by weight ofmethoxyl groups and 1 to 15% by weight of hydroxypropoxyl groups, basedon the nonionic cellulose ether, and the polymers of phthalic acidand/or terephthalic acid known from the prior art or derivativesthereof, more particularly polymers of ethylene terephthalates and/orpolyethylene glycol terephthalates or anionically and/or nonionicallymodified derivatives thereof. They are active in only small quantities.Accordingly, their content is preferably from 0.2 to 10% by weight and,more preferably, up to 5% by weight.

The function of redeposition inhibitors is to keep the soil detachedfrom the fibers suspended in the wash liquor and thus to preventdiscoloration. Suitable redeposition inhibitors are water-soluble,generally organic colloids, for example the water-soluble salts ofpolymeric carboxylic acids, glue, gelatine, salts of ether carboxylicacids or ether sulfonic acids of starch or cellulose or salts of acidicsulfuric acid esters of cellulose or starch. Water-soluble polyamidescontaining acidic groups are also suitable for this purpose. Solublestarch preparations and other starch products than those mentionedabove, for example degraded starch, aldehyde starches, etc., may also beused. Polyvinyl pyrrolidone is also suitable. However, cellulose ethers,such as carboxymethyl cellulose (Na salt), methyl cellulose,hydroxyalkyl cellulose, and mixed ethers, such as methyl hydroxyethylcellulose, methyl hydroxypropyl cellulose, methyl carboxymethylcellulose and mixtures thereof, and polyvinyl pyrrolidone may also beused, for example in quantities of 0.1 to 5% by weight, based on thedetergent.

Other suitable ingredients of the detergents/cleaning products arewater-soluble inorganic salts, such as bicarbonates, carbonates,amorphous silicates or mixtures thereof. Alkali metal carbonate andamorphous alkali metal silicate, above all sodium silicate with a molarNa₂ O to SiO₂ ratio of 1:1 to 1:4.5 and preferably 1:2 to 1:3.5, areparticularly preferred. The sodium carbonate content of thedetergents/cleaning products is preferably up to 20% by weight andadvantageously between 5 and 15% by weight. The sodium silicate contentof the detergents/cleaning products is generally up to 10% by weight andpreferably between 2 and 8% by weight.

The term "amorphous" in the context of the invention also encompasses"X-ray amorphous". This means that, in X-ray diffraction experiments,the silicates do not produce any of the sharp X-ray reflexes which aretypical of crystalline substances, but instead only one or more maximaof the scattered X-rays which have a width of several degrees of thediffraction angle. However, it is highly possible and may even lead toparticularly favorable builder properties that, in electron diffractionexperiments, the silicate particles produce intergrown or even sharpdiffraction maxima. This may be interpreted to mean that the productshave microcrystalline regions ranging from 10 to a few hundred nm insize.

These X-ray amorphous silicates--like some commercially availablecompounds of carbonates and amorphous silicates--are suitable for partlyor completely replacing conventional builders, such as phosphate,zeolite and crystalline layer silicates. If such substances are used,their content may even exceed the quantities mentioned above forcarbonates and amorphous silicates. Contents of up to 40% by weight oreven 60% by weight are entirely within the scope of the invention.

According to the teaching of earlier German patent application P 43 19578.4, alkali metal carbonates may also be replaced by sulfur-free C₂₋₁₁amino acids optionally containing another carboxyl and/or amino groupand/or salts thereof. According to the invention, the alkali metalcarbonates are preferably replaced partly or completely by glycine orglycinate.

Among the compounds yielding H₂ O₂ in water which serve as bleachingagents, sodium perborate tetrahydrate and sodium perborate monohydrateare particularly important. Other useful bleaching agents are, forexample, sodium percarbonate, peroxypyrophosphates, citrate perhydratesand H₂ O₂ -yielding peracidic salts or peracids, such as perbenzoates,peroxophthalates, diperazelaic acid or diperdodecanedioic acid. Thecontent of bleaching agents in the tablets is preferably 5 to 25% byweight and, more preferably, 10 to 20% by weight, perborate monohydrateand/or percarbonate advantageously being used.

In order to obtain an improved bleaching effect where washing is carriedout at temperatures of 60° C. or lower, bleach activators may beincorporated in the preparations. Examples of bleach activators areN-acyl or O-acyl compounds which form organic peracids with H₂ O₂,preferably N,N'-tetraacylated diamines, p-(alkanoyloxy)-benzenesulfonate, also carboxylic anhydrides and esters of polyols, such asglucose pentaacetate. Other known bleach activators are the acetylatedmixtures of sorbitol and mannitol which are described, for example, inEuropean patent application EP-A-0 525 239. The content of bleachactivators in the bleach-containing tablets is in the usual range,preferably between 1 and 10% by weight and, more preferably, between 3and 8% by weight. Particularly preferred bleach activators areN,N,N',N'-tetraacetyl ethylenediamine (TAED),1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine (DADHT) and acetylatedsorbitol/mannitol mixtures (SORMAN).

Where the detergents are used in machine washing processes, it can be ofadvantage to add typical foam inhibitors to them. Suitable foaminhibitors are, for example, soaps of natural or synthetic origin with ahigh percentage content of C₁₈₋₂₄ fatty acids. Suitablenon-surface-active foam inhibitors are, for example, organopolysiloxanesand mixtures thereof with microfine, optionally silanized silica andalso paraffins, waxes, microcrystalline waxes and mixtures thereof withsilanized silica or bis-stearyl ethylenediamide. Mixtures of variousfoam inhibitors, for example mixtures of silicones, paraffins or waxes,are also used with advantage. The foam inhibitors, more particularlysilicone- or paraffin-containing foam inhibitors, are preferably fixedto a granular water-soluble or water-dispersible support. Mixtures ofparaffins and bis-stearyl ethylenediamides are particularly preferred.

Preferred salts of polyphosphonic acids are the neutrally reactingsodium salts of, for example, 1-hydroxyethane-1,1-diphosphonate,diethylenetriamine pentamethylene phosphonate or ethylenediaminetetramethylene phosphonate which are used in quantities of 0.1 to 1.5%by weight.

Suitable enzymes are those from the class of proteases, lipases,amylases, cellulases and mixtures thereof. Enzymes obtained frombacterial strains or fungi, such as Bacillus subtilis, Bacilluslicheniformis and Streptomyces griseus, are particularly suitable.Proteases of the subtilisin type are preferably used, proteases obtainedfrom Bacillus lentus being particularly suitable. Enzyme mixtures, forexample mixtures of protease and amylase or protease and lipase orprotease and cellulase or mixtures of cellulase and lipase or mixturesof protease, amylase and lipase or protease, lipase and cellulase, butespecially cellulase-containing mixtures, are of particular interest.Peroxidases or oxidases have also proved to be suitable in some cases.The enzymes may be adsorbed to supports and/or encapsulated inshell-forming substances to protect them against prematuredecomposition. The percentage content of enzymes, enzyme mixtures orenzyme granules may be, for example, of the order of 0.1 to 5% by weightand is preferably from 0.1 to around 2% by weight.

The tablets or compounds may contain derivatives of diaminostilbenedisulfonic acid or alkali metal salts thereof as optical brighteners.Suitable optical brighteners are, for example, salts, of4,4'-bis-(2-anilino-4-morpholino-1,3,5-triazinyl-6-amino)-stilbene-2,2'-disulfonicacid or compounds of similar composition which contain a diethanolaminogroup, a methylamino group, an anilino group or a 2-methoxyethylaminogroup instead of the morpholino group. Brighteners of the substituteddiphenyl styryl type, for example alkali metal salts of4,4'-bis-(2-sulfostyryl)-diphenyl,4,'-bis-(4-chloro-3-sulfostyryl)-diphenyl or4-(4-chlorostyryl)4'-(2-sulfostyryl)-diphenyl, may also be present.Mixtures of the brighteners mentioned above may also be used.

In one preferred embodiment of the invention, tablets are produced whichcontain 15 to 40% by weight, preferably 18 to 35% by weight and morepreferably 20 to 30% by weight of anionic or anionic and nonionicsurfactants, the anionic surfactant content preferably being above 10%by weight and the ratio by weight of anionic surfactants to nonionicsurfactants being 5:1 to 1:2. Particularly preferred anionic surfactantsare alkyl benzene sulfonates and alkyl sulfates and also soaps.Preferred nonionic surfactants are ethoxylated C₁₂₋₁₈ fatty alcohols oroxoalcohols and alkyl glycosides. In addition, preferred tablets contain10 to 60% by weight, preferably 15 to 50% by weight and more preferably20 to 40% by weight of such builders as zeolite A and/or zeolite P,crystalline layer silicates of the SKS-6® type or amorphous or X-rayamorphous silicates and also carbonate/silicate compounds with acorrespondingly high calcium binding capacity.

In another preferred embodiment of the present invention, tablets areproduced which contain 40 to 60% by weight of compounds of which 10 to90% by weight consist of anionic surfactants, advantageously alkylbenzene sulfonates and/or alkyl sulfates, and 10 to 90% by weight ofbuilders, hydrated salts and/or disintegrating agents.

Other advantageous tablets additionally contain compounds which are freefrom anionic surfactants and contain builders, advantageously zeolite Aand/or zeolite P, and 10 to 40% by weight of nonionic surfactants.

EXAMPLES Example 1

A tablet was produced from the compounds, powders and liquids mentionedbelow in accordance with the teaching of International patentapplication PCT/EP94/01330. To this end, a homogeneous mixture wasprepared from the components in a mixer, subsequently introduced into amold and precompressed for 10 seconds under a pressure of 13 N/cm² (theforce applied to the circular surface measured 35N over an area of 2.7cm²). The tablet was then microwaved at 2,450 MHz/700 watts. Thetreatment lasted 7 seconds. A temperature of 60° C. was not exceededduring the microwave treatment.

Composition:

3% by weight of anionic surfactant compound (consisting of 90.5% byweight of C₁₂₋₁₈ alkyl sulfate, 5% by weight of sodium sulfate, restwater)

41% by weight of spray-dried granules (consisting of 10% by weight ofsodium dodecyl benzene sulfonate, 3% by weight of C₁₂₋₁₈ sodium fattyacid soap, 1.5% by weight of tallow fatty alcohol containing 5 ethyleneoxide groups, 60% by weight of zeolite (expressed as water-free activesubstance), 5% by weight of sodium carbonate, 2.5% by weight of sulfateand other salts from solutions and raw materials and 18% by weight ofwater)

3% by weight of a granular foam inhibitor based on silicone oil (15% byweight)

14% by weight of sodium perborate monohydrate

7% by weight of a granular bleach activator based on tetraacetylethylene-diamine

1% by weight of sodium carbonate (calcined soda)

1% by weight of silica

2% by weight of zeolite powder

1% by weight of copolymeric salt of acrylic acid and maleic acid

3% by weight of a 30% aqueous solution of this copolymer

11% by weight of sodium hydrogen carbonate

9% by weight of citric acid

1% by weight of protease-based enzyme granules

2% by weight of C₁₂₋₁₈ alcohol containing 7 ethylene oxide groups

1% by weight of perfume

The tablet had a high breaking strength under pressures of 7.4 to 37N/cm².

The tablet also had a high disintegration rate in water. Large parts ofthe tablet had disintegrated after only 1 minute, 100% of the tablethaving disintegrated after 5 minutes.

Percarbonate may be used instead of the perborate. In addition, the soapmay be used in the form of separate soap granules containing more than80% by weight of soap and, in addition, soda and polymericpolycarboxylates.

Example 2

A tablet was produced from the compounds, powders and liquids mentionedbelow in accordance with the teaching of International patentapplication PCT/EP94/01330. To this end, a homogeneous mixture wasprepared from the components in a mixer, subsequently introduced into amold and precompressed for 10 seconds under a pressure of 2.6 N/cm² (theforce applied to the circular surface measured 7N over an area of 2.6cm²). The tablet was then microwaved at 2,450 MHz/700 watts. Thetreatment lasted 7 seconds. A temperature of 65° C. was not exceededduring the microwave treatment.

Composition:

3% by weight of anionic surfactant compound (consisting of 90.5% byweight of C₁₂₋₁₈ alkyl sulfate, 5% by weight of sodium sulfate, restwater)

48% by weight of spray-dried granules (consisting of 10.3% by weight ofsodium dodecyl benzene sulfonate, 2.9% by weight of C₁₂₋₁₈ sodium fattyacid soap, 1.5% by weight of tallow fatty alcohol containing 5 ethyleneoxide groups, 56.4% by weight of zeolite (expressed as water-free activesubstance), 3.4% by weight of sodium carbonate, 2.3% by weight ofpolyvinyl pyrrolidone, 5.4% by weight of copolymeric salt of acrylicacid and maleic acid, 1% by weight of other salts from solutions and rawmaterials and 16.8% by weight of water)

3% by weight of a granular foam inhibitor based on silicone oil (15% byweight)

3% by weight of sodium carbonate (calcined soda)

1% by weight of silica

3% by weight of zeolite powder

2% by weight of copolymeric salt of acrylic acid and maleic acid

11% by weight of sodium hydrogen carbonate

14% by weight of sodium citrate

1% by weight of protease-based enzyme granules

5% by weight of C₁₂₋₁₈ alcohol containing 7 ethylene oxide groups

1% by weight of perfume

5% by weight of sodium silicate (Na₂ O:SO₂, 1:2.0, containing 18% byweight of water)

The tablet had a high breaking strength under pressures of 7.4 to 22N/cm².

In addition, the tablet had a high disintegration rate in water. Largeparts of the tablet had disintegrated after only 0.5 minutes, 100% ofthe tablet having disintegrated after 4 minutes.

We claim:
 1. A process for producing detergent tablets containing morethan 10% by weight of anionic surfactant wherein said detergent tabletscontain detergent components which are at least partly in hydrated formand said anionic surfactant is present as a mixture of different anionicsurfactants consisting essentially of exposing a mixture of saiddetergent components and said anionic surfactant to microwaves in thefrequency range from 3 to 300,000 MHZ wherein said detergent componentsand said anionic surfactants are encapsulated with a hydrated materialprior to exposing said mixture to microwaves, said hydrated material isselected from the group consisting of amorphous alkali metal silicates,alkali metal carbonates and bicarbonates, alkali metal sulfates andbisulfates, zeolite, citrates and acetates.
 2. A process as in claim 1wherein said detergent tablets further contain a nonionic surfactant. 3.A process as in claim 2 wherein said nonionic surfactant is selectedfrom the group consisting of an ethoxylated primary alcohol containing 8to 18 carbon atoms and 1 to 12 moles of ethylene oxide per mole ofalcohol, alkyl glycosides, alkoxylated fatty acid alkyl esters, amineoxides, and polyhydroxy fatty acid amides.
 4. A process as in claim 1wherein said detergent tablets contain at least 35% by weight of saidanionic surfactant, based on the weight of said detergent tablets.
 5. Aprocess as in claim 1 wherein said hydrated material is present in anamount of 1% to 30% by weight, based on the weight of said detergenttablets.
 6. A process as in claim 1 wherein prior to exposing saidmixture to microwaves, said process further consists essentially of thestep of subjecting said mixture to compression.
 7. A process as in claim1 which further consists essentially of adding to said mixture of saiddetergent components and said anionic surfactant a tablet disintegratingagent in an amount of 0.5% to 30% by weight, based on the weight of saiddetergent tablets.
 8. A process as in claim 7 wherein saiddisintegrating agent is encapsulated with a hydrophobic materialselected from the group consisting of paraffin oils and silicone oils.9. A process as in claim 1 wherein said anionic surfactant is selectedfrom the group consisting of sulfonates, sulfates, sulfonated fatty acidglycerol esters, sulfuric acid mono-esters of primary alcohols andethoxylated derivatives thereof, salts of alkyl sulfosuccinic acid, andsoap.
 10. A process as in claim 1 wherein said detergent componentsconsist essentially of inorganic or organic builders.
 11. A process asin claim 10 wherein said builders are present in an amount of 10% to 60%by weight, based on the weight of said detergent tablets.